离子液体1-丁基-3-甲基咪唑溴盐对CO2电催化还原的活化机理研究

Study on Activation Mechanism of Ionic Liquid [Bmim] Br for CO2 Electrocatalytic Reduction

利用线性伏安、塔费尔动力学和电化学交流阻抗的表征手段,研究了离子液体1-丁基-3-甲基咪唑溴盐([Bmim]Br)和碳酸丙烯酯构成的电解液中,离子液体对CO 2在Ag片电极电还原过程中的活化作用机理。线性伏安和塔费尔动力学测试表明:以[Bmim]Br作电解质时,CO2电催化还原的起始还原电位正移,并有效促进CO2被还原为CO2·–。电化学交流阻抗测试发现:咪唑阳离子[Bmim]+在Ag片电极上发生吸附,并与CO2·–相互作用形成了[Bmim-CO2]ad中间体,降低了电催化还原CO2反应的活化能,促进了CO2的转化。

Absrtact: The activation mechanism of ionic liquids for CO2 electrocatalytic reduction on Ag electrode sheet was studied by means of linear voltammetry,Tafel kinetics and electrochemical impedance characterization.The electrolyte was constituted of ionic liquid 1-butyl-3-methylimidazolium bromide( [Bmim]Br) and propylene carbonate. The linear voltammetry and Tafel kinetic measurements show that electrolyte [Bmim]Br can positively shift the initial reduction potential of CO2,and effectively promote the reduction of CO2 to free radical of CO2·-. The electrochemical alternating current impedance measurements further show that imidazole cation [Bmim]+ adsorbs on Ag sheet electrode and forms [Bmim-CO2]ad intermediates by interacting with CO2·-,which reduces the activation energy of CO2 electrocatalytic reduction and then effectively accelerates the conversion of CO2.